Relieving mechanism for grinding machines



' Dec. 6, 1927. v I 1,651,432

J. BA'FH ET AL RELIEVING MECHANISM FOR GRINDING MACHINES Filed March 21,1924 4 Sheets-Sheet 1 1&1 g; 69 r"; 65 i g .2? 26 5 i Dec.6,1927 I1,651,432.

J. BATH ET AL RELIEVING MECHANISM FOR GRINDING MACHINES Fild March 21.1924 4 Sheets-She et 2 Dec. 6, 1927.

1,651,432 J. BATH ETYAL RELIEVE G MECHANISM FOR GRINDING MACHINES FiledMarch 21. 1924 4 Sheets-Sheet 5 Dec. 6, '1927. 1,651,432

J. BATH ET AL RELIEVING MECHANISM FOR GRINDING MACHINES 7 ,F JE: 3 2L 5commonl Patented Dec. 6, 1927.

' UNITED STATES PATENT OFFICE. i

JOHN DATE AND ERNEST A. WALKER, O1 WORCESTER, IASSACKUBITIB,

. BY 1mm ABSIGN'IENTS, '10 SAID JOHN BATH.

ABBIGNOBS,

BILEVING I03 GRINDING meme Application filed larch 81, 1924. Serial Io.700,880.

This invention relates to a grinding machine capable of neral operationbut particularl designed for grmdin taps and other similar flutedarticles. 1%16 tags are supported upon centers uring the grin ing rationand are fluted lengthwise between t e successive lands or rows of teeth.These flutes or grooves may be disposedeither axially or spirally of thetap. It is the general object of our invention to rovide an improvedconstruction of grindmg machine by which the teeth of a tap may berelieved rearwardly, so that the frictional resistance of the teeth maybe thereby large- 1y reduced.

A further object of our invention is to provide a construction by whichthe teeth of a tap may be relieved whether they are arra ed axially orspirally of the tap.

ith these objects in view, im rtant features of our invention relate tot e provision of a work sup ortin table mounted for movement toward androm the grinding wheel and to the provision of a cam mechanism formovingthe table in timed means forindicating relation to the rotation ofthe work. We have also provided an improved device for longitudinallyadjusting the work table; t e relative 'tion of the wheel and the work,and ot er arrangements and combinations of arts which will behereinafter described an more particularly inted out in the appendedclaims. A pre erred term of the invention is shown in the drawings, inwhich Fig. 1 is a frontelevation of a portion of a grinding machineembodying our improveinents;

Fig". 2 is a lett hand end elevation thereof,

looking in the direction oi the arrow 2 in 3 is a detaii plan view,looking in the direction of the arrow 3 in Fig. 2;

Fin. 4 is a detaii' plan View, limiting in the direction of the arrow 4;in Fig. 1;

5 is a partial sectionai elevation, taken along the line 5-5 in Fig. i;

Fig. 2 is a partial sectioned plan view, showing: mechanism foradjusting the table longituuinali F is a transverse sectionai elevation,twee along the has "E -t Fig. 6;

Fig. 8 is a detail front elevation of certam parts, looking in thedirection of the arrow 8 in Fig. 6;

Fig. 9 IS an end elevation of a part to be described, looking in thedirection of the arrow 9 in Fig. 6;

Fig. 10 is a partial diagrammatic view showing a selected cam lay-outF1g. 1'1 1s a detail front elevation, showing a mod1fied formof tableadjusting mechamsm;

Fig. 12 is a transverse sectional elevation taken along the line 12-12in Fi 11; and

Fi 13 1s a detail plan view, ooking in the irection of the arrow 13 inFig. 12.

Referring particularly to Figs. 1 and 2, we have indicated portions of.a grinding mach ne comprising a base or frame a grinding wheel W, awork sup rting table 21, a tail stock 22 lo tudinall adjustable on thetable 21, and a ead stocli 23 fixed to the table 21. The tail stock 22and head stock 23 are provided with centers 24 and 25 upon which a tapor other piece of work maly be mounted for rotation.

. he hve center 25 is carried upon a spindle 26 which is driven throughreduction gearing from a suitable source of power, such as a drivingbelt 27. The grinding wheel W (Fig. 3) is rotatably mounted in a wheelcarriage 30 which is movable longitudinally of the machine uponguideways 31 positive 1 ar drive through suitable change ring rem thespindle 26. fine nrran ement of gearing is indicated in Fig. 2, andcomprises a pinion 33 on the spindle 2'5, an intermediate gear 34, apinion 35, a pinion 38, second intermediate 37, and a gear 38 on thelead screw 32. substituting diiierent combinations of gears in the geartrain indicated, the wheel cor rings and wheat may he moved amaiiv tocorrespond with the desired ieari of tit e thread to be The table 21supported upon a rock shaft {Fig 5} which is iongitudinaliy secured in arecess up r surface oi base or Bearing brcchzets seemed to the frontface of tahie 21 o support a cam t2 which is count by gears 43, 44 and45 (Fig. 2) to the work spindle 26. By changing the relative sizes ofthe gears 43 and 45, any deslred speed relation may be secured betweenthe spindle 26 and the cam shaft 42.

One ormore cams 47 are fixed on the cam shaft 42 and are thus rotated intimed relation to the work spindle 26. A cam roll 48 (Fig. 5) is mountedin a bearing member 49 which is longitudinally adjustable in guidewayson a bracket. 50 fixed to the front of the base 20. A preferred form ofbearing for a the roll '48 is indicated in Fig. 5, in which the roll isprovided with axially extended bearing portions 51 which rest in o nrecesses 52 in the bearing'member 49. e inner portion of the member 49may also be desirably recessed to form an oil chamber 53 from which theroll 48 is effectively lubricated.

A portion of a cam 47 is indicated in Fi 10 in which, however, the rise,fall and dwe l of the cam are much exaggerated for the sake ofclearance. In the cams as actually used, the rise and fall of the cam iscommonly from .002 to .006 an amount too small to be indicated to scaleon the drawin When a plurality of earns 47 are provi ed, successive camsmay be provided with increasing amounts of rise and fall, or the camsmay be provided with difierent numbers of hi h and low points.

The rol bearing member 49 may be adjustable manually to cause the roll48 to cooperate with any desired cam 47 and mag be secured in adjustableposition by bin ing bolts 54 (Fig. 1). In this manner, the amount ofstock removed for clearance at the rear of each row of teeth may beselected and varied as desired.

If the number of high points in the selected cam 47 corresponds to thenumber of rows of teeth in the tap, the cam shaft 42 will be ared torotate at the same speed as the spin e 26, but if the cam has adifferent number of high points, the relative speed of the spindle andshaft will be so arranged that one high point of the cam will bepreaented for each row of teeth.

If the tap is spirally fluted, the rotation of the cam shaftwill notcorrespond exactly to the rotation of the work spindle, but will varytherefrom by a differential amount so that the point of relieving actionwill follow the helical arran ment of the teeth.

Reference to ig. 5 will indicate that the rock shaft is at substantiallyequal dis- 1h tances from the cam roll 48 and from the work center 25 inthe spindle 26. The relieving movement of the work is thus substantiallyequal to the actual amount of rise and fall on the cam 47. On account ofthe large mass and weight of the parts moved by the cam 47, the partsmove smoothly and positively and the relieving is performed withexceptional accuracy.

It is desirable to provide means for slightl adjusting the table 21longitudinally of the machine, so that the teeth of the tap mounted uponthe centers 24 and 25 may accurately engage the bevelled cutting edge ofthe wheelVV. For this purpose, we have provided the construction shownin Figs. 6 to 9 inclusive, comprising a bracket or frame secured to theend of the'rock shaft 40 by a. bolt 51. The frame 50 is recessed toprovide bearing surfaces 52 and 53 which are engaged by therear'portions of a pair of bell crank levers 54 pivoted at 55 and 56 ina bracket 57 which in turn is secured to the under side of the table 21by bolts 58 (Fig. 7).

Adjusting screws 59 are threaded in the bracket 57 and extend throughthe front portion of the table 21. By turning one or the other of theadjusting screws 59, the corresponding bell crank 54 may be forcedagainst a. bearin surface 52 or 53, thus causin 1ongitudina movement ofthe table 21 relative to the frame 50 and relative to the grinding wheelW. When the desired position is attained, the screws 59 ma be tightenedto hold the parts firmly in a justed position.

In Fig. 4, we have shown an index finger 60 mounted on the wheelcarriage 30 and extending over a scale 61 on the tail stock 22.

This index 60 is convenient for quickly resetting the wheel and work toa desired axial relation.

A modified form of table adjustin mechanism is. shown in Figs. 11,12 am?13 and comprises a member 61 loosely mounted on the rock shaft 40between fixed collars 62 and 63. The member 61 is provided withoppositely inclined or bevelled surfaces 64 and 65 which are engaged bythe conical ends of I adjusting screws 66 threaded in the table 21. Thepart 61 is rovided with projections or shoulders as in icated in Fig. 12which prevent more than slight angular movement of the part 61 on therock shaft 40. B relatively adjusting the screws 66, the taiil may bemoved longitudinally to a limited extent for relative adjustment of the,wheel and work, as with the preferred arrangement. I

By providing two driving studs 68 (Fig. 1) on the driving plate 69 onthe work spindle 26, the dog on the work may be placed against eitherone or the other of the studs. accordance with the direction ofrotation. so that taps of either hand may be ground and may be relievedby the use of the same relieving cam, and the wheel may be caused to cutin both directions of travel of the wheel carriage.

IVhen no relieving action is desired, a wedge 70 (Fig. 12) may beinserted between titl ,the work support to car nouns:

provided on the head stock 23. As shown,

this device comprises a' plunger 72 and a pointer 73 by which the motionof the plunger is reproduced, much enlarged, on a scale A contact 75 isthreaded in a stand 7 6 fixed on a portion of the base 20.. As the table21 swings forward and rearward, the plunger 72 is pressed against therelatively fixed contact 7 5 and shows the movement of the table, muchenlarged, on the scale 74. This is of convenience 'in setting the work,as the cams are so nearly circular that it is difiicult to distinguishthe rise. and fall thereon.

Having thus described our invention and the advanta es thereof, we donot wish to be limited to t e details herein disclosed other wise thanas set forth in the claims, but what we claim is I 1. In a grindingmachine, a grinding wheel, means to rotate said wheel, means to movesaid wheel axially, a work support, means to rotate the work thereon,and variably actuated relieving mechanism to move the work support tocarr the work toward and from the inding w eel.

2. In a grinding machine, a grinding wheel, means to rotate said wheel,means to move said wheel axiall a work support,

means to rotate the wor thereon, and variably actuated relievingmechanism to move the work support to carry the work toward and from t egrinding wheel, said wheel, said work and said relievin mechanism be ingsimultaneously actuate in timed relation to each other. a

3. In a grinding machine, a grindin wheel, means to rotate said wheel,means to move said wheel axially, a work support, means to rotate thework thereon, and variably actuated relieving mechanism to move the worktoward and from the grinding wieel, said relieving mechanism including acam and means to rotate said cam in a definite speed relation to therotation of the Work.

4. In a grinding machine, a grindin wheel, a work table oscillatabletoward at: from said wheel, means to support androtate the work thereon,a cam shaft'rotatahly mounted on said table, a plurality of relievingcams mounted thereon, a bearing ele= mentislidably mounted on saidmachine below said cam shaft and adapted to cooperate with a selectedone of said cams and means torotate said selected cam in fixed relationto the rotation of the work.

' 5. In a grinding machine, a grinding wheel, a work table, means tosupport and rotate the work thereon, means to oscillate said work tabletoward and from said wheel pomprising'a cam shaft rotatably mountedshaft and cams in fixed relation to the rotation of the work, and aco-operating bearing element selectively movable to osition forengagement with any one of said cams.

6. In a grinding machine, a grinding wheel, means to rotate said wheel,means to move said wheel axially, a work support, means to rotate thework thereon, selectively actuated relieving mechanism to move the worksupport to'carry the work toward and from the grinding wheel, and meansto actuate said relieving mechanism in difierem' tial relation to therotation of the work, whereby spirally fluted work may be relieved 7. Ina grinding machine, a grimlin wheel, a work table, means to support anrotate the work thereon, a fixed bearing on which said table is pivoted,selectively operated means LO rock said table and work toward and'fromthe wheel, and means to adjust said table longitudinally relative to thegrinding wheel.

8. In a grinding machine, a grinding wheel, a work table, means tosupport an rotate the work thereon, a. bearin for said table, means torock said table an work toward and from the grindin wheel, a mem berfixed longitudinally of 4216 machine and having opposed bearingsurfaces, a pair of levers mounted on said table and engagin saidopposed surfaces-on said member, an manual means to separately adjustsaid levers and thereby move said table longitudinally relative to saidinding wheel.

9. In a grinding mac inc, a grin wheel, a work table, means to supportand rotate the work thereon, a bearin for said table, means to rock saidtable an work toward and from the grinding wheel, a member fixedlongitudinally of the machine and having op osed bearing surfaces a pairof hell crank overs mounted on said table and engaging. the opposedsurfaces of safiolmemher, and a pair of adjusting screws threaded in thefront of said table and engaging said levers, said screws beingseparately and manually movable to force a selected lever against itsbearing surface to move said table longitudinally in said machine in adesired direction.

10. In a grinding machine, a grinding wheel, a wheel carriage, means tomove said wheel and carriage longitudinally of the work, a tailcenteradjustahly lined thereon and having graduated index scale, and apointer mounted on said wheel carriage and ctr-operating with said scaleto wheel position.

a machine, agrinding wheel, a work table, means to support and rotatethe work thereon, fixed bearing on which said ispivoted, means to rocktill res

said table and work toward and from the wheel, and means to ad'ust saidtable longitudinally relative to t e grinding wheel said meanscomprising a member mounted l in fixed axial osition and havin op sitelyinclined beveled surfaces, an a justing screws engaging said bevelledsurfaces and effective to move said table axially relatively to saidgrinding wheel.

12. In a grinding machine, a grindin wheel, a work table, means tosupport an rotate the work thereon, a rock shafton which said table ispivoted, means to rock said table and work toward and from the wheel,and means to adjust said table longitudinally relative to the grindingwheel, said means com rising a member mounted on said rock s aft infixed axial position and having oppositely inclined bevelled surfacesand ad'usting screws having substantial] conicai end portions engagingsaid beveled surfaces and effective to move said table axially relativeto said grinding wheel.

13. In a grinding machine, a grinding II wheel, a work table, means tosupport and rotate the work thereon, relieving cams rotatably mounted onsaid table, a beari element co-operating with a selected one 0 saidcams, and an indicatin device b which the movement of the tab e is reproneed on 80 a greatly enlarged scale.

14. In a inding machine, a grinding wheel, a W05; table, means tosupport an rotate the work thereon, relieving cams rotatably mounted onsaid table, a bearin element cooperating with a selected one 0 saidcams, an indicating device mounted to move with said table, and a fixedelement co-operating with said device to indicate thereon the movementof the table on a much enlarged scale. p

15. In a rinding machine, a grindin wheel, a wor table, means to supportand rotate the work thereon, means to oscillate said work table towardand from said wheel 45 comprising a plurality of relieving cams ofvarying contours rotatably mounted on said table, a bearing elementslidable below said cams for engagement with a selected one thereof,means to rotate said "selected cam in fixed relation to the rotation ofthe work and an oil bath for said bearing element.

In testimony whereof we have hereunto afiixed our signatures.

JOHN BATH. ERNEST A. WALKER.

